my huge file size is causing blender to freeze every few seconds
The scene takes up almost 2 GB RAM, if you are indeed using an old laptop, this might be the bottleneck, especially if you have a web browser open with a few tabs, too.
In windows you should always have an eye on the task manager, especially the performance tab.

As Anders, I would not call this low poly aswell, with almost 50k polygons. That is why rob suggested to delete the heads, as they are making up the majority of those. You could however dissolve a lot of edges, too...